According to the WABetaInfo the WhatsApp team is working on implementing a function in the messenger with help of which users could export chats when changing their phone number.
So, according to the source, when the user decides to change or add a new SIM-card, the program will automatically replace the number with the updated one. Thus, in order to export chats along with media and other files, you just need to connect the device to your WhatsApp account.
In addition, WhatsApp plans to add the ability to transfer data between devices with different operating systems by clicking on one button. Another function may appear in the messenger, thanks to which users will be able to use WhatsApp Web without an Internet connection. It is assumed that all the listed innovations will be added in one of the next updates.